(a) Field of the Invention
The present invention relates to a concrete admixture additive for water reduction and to the process of making the same.
(b) Description of the Related Art
In a typical concrete mixing process, a large amount of water is added to increase flowability of the concrete. However, water overdose lowers concrete compression strength and adversely affects other properties. While on the contrary, lack of water causes concrete slump and deterioration, which is harmful to a construction process. Many chemical additives have been invented in the past to improve concrete flowability without the need of increasing the amount of water.
Traditional concrete water reducers are formed by mixing lignin as main component with naphthalene sulfonic acid sodium salt. Although the cost of such kind of additives is relatively low, they cannot provide desirable concrete water reduction when the effective content in the concrete is low. For example, when a type F water reducer, which consists mainly of naphthalene-based compounds, is used, rapid concrete slump will result.
Recently copolymers of acrylic acid or maleic anhydride and alkenyl ethers and their derivatives have been found to improve concrete admixture flowability. [Japanese Patent Publication (Kokai) Nos 285140/88 and 163108/90]. Besides, copolymers of maleic acid and its salt and ester derivatives and hydroxy-terminated allyl ether and copolymers of maleic acid and partially esterified styrene are known to enhance concrete admixture flowability [U.S. Pat. Nos. 4,471,100 and 5,158,996]. Such chemical reagents are classified as carboxylic type additives. But those concrete additives still can not provide all the required properties. For example, although esterified acrylic acid copolymers provide good concrete admixture flowability, they also prolong the hardening time.
In view of the above, a new family of concrete admixture additives is disclosed and claimed in the present invention. These additives, even at a relatively low additive level, can provide improved water reduction, increase concrete flowability, reduce concrete slump and enhance compression strength. In addition, the processes of making such concrete admixture additives are also disclosed and claimed.